Introduction

Function block data type families are:

Illustration:

Function blocks are entities containing:

  • input and output variables acting as an interface with the application

  • a processing algorithm that operates input variables and completes the output variables

  • private and public internal variables operated by the processing algorithm

Illustration

Function block:

User Function Block (DFB)

The user function block types (Derived Function Blocks) are developed by the user using one or more languages (according to the number of sections). These languages are:

  • Ladder language

  • Structured Text language

  • Instruction List language

  • Functional block language FBD

A DFB type can have one or more instances where each instance is referenced by a name (symbol) and possesses DFB data types.

Elementary Function Block (EFB)

Elementary Function Blocks (EFBs) are provided by the manufacturer and are programmed in C language.

The user can create his own EFB for which he will need an optional software tool "SDKC".

An EFB type can have one or more instances where each instance is referenced by a name (symbol) and possesses EFB type data.